fix: decode .bin to PNG via PPM blob, not importImagePixels

The Imagick extension on the server (3.7+) requires importImagePixels
to receive an array of ints, not a string blob, so the previous code
500'd. Wrap the raw RGB bytes in a PPM (P6) header and let Imagick
decode it via readImageBlob — same result, no 70 MB-array detour.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/Controller/DeviceApiController.php

@@ -231,10 +231,10 @@ class DeviceApiController extends AbstractController
 
     private function renderBinToPng(string $binPath, string $pngPath, int $width, int $height): void
     {
-        $bin    = (string) file_get_contents($binPath);
+        $bin   = (string) file_get_contents($binPath);
-        $len    = strlen($bin);
+        $len   = strlen($bin);
-        $rgb    = '';
+        $rgb   = '';
-        $white  = self::PALETTE[0x1];
+        $white = self::PALETTE[0x1];
         for ($i = 0; $i < $len; $i++) {
             $byte = ord($bin[$i]);
             foreach ([($byte >> 4) & 0xF, $byte & 0xF] as $idx) {
@@ -243,9 +243,13 @@ class DeviceApiController extends AbstractController
             }
         }
 
+        // Wrap the raw RGB bytes in a PPM (P6) header so Imagick can decode the
+        // blob directly. importImagePixels would also work but its current
+        // signature requires an array of ints, which is ~70 MB for an 800×480.
+        $ppm = "P6\n{$width} {$height}\n255\n" . $rgb;
+
         $im = new \Imagick();
-        $im->newImage($width, $height, new \ImagickPixel('white'));
+        $im->readImageBlob($ppm);
-        $im->importImagePixels(0, 0, $width, $height, 'RGB', \Imagick::PIXEL_CHAR, $rgb);
         $im->setImageFormat('png');
         $im->writeImage($pngPath);
         $im->destroy();